Hypersensitivity reaction after inhalation of a lactose-containing dry powder inhaler.

Milk protein allergy-induced reactions from lactose-containing dry powder inhalers (DPIs) have not been widely described in the literature. Lactose is a common inactive ingredient in many pharmaceutical products that is used to enhance the stability of active substances in medicinal products, including asthma medications. Contamination of lactose with milk proteins has been identified in reports of inhaled corticosteroid product lot testing. Serious respiratory sequelae may follow after the inhalation of a DPI corticosteroid in a patient with milk protein allergy because DPIs that contain lactose may be contaminated with milk proteins. Lactose-containing DPIs are contraindicated in patients with milk protein allergy. Although manufacturers identify this contraindication in product package inserts, some drug references may not include this information and health care professionals may lack awareness. Clinicians should consider reviewing multiple medication resources for warnings and contraindications of medications to prevent complications. We describe a refractory asthma exacerbation secondary to a hypersensitivity reaction following administration of a lactose-containing DPI corticosteroid and long-acting β2 agonist combination in a child with a milk protein allergy.